| 
 | 
 | 
If a line intersects one of two parallel lines, it must intersect the other also. This Axiom is equivalent to the Parallel Axiom.
References
Dunham, W.  ``Hippocrates' Quadrature of the Lune.''  Ch. 1 in 
  Journey Through Genius: The Great Theorems of Mathematics.  New York: Wiley, p. 54, 1990.